Michelle Depew Are you experienced with electrical wiring, and do you have a DMM (digital multimeter) to use to check connections etc?
This is a DC system, and in DC systems, red is positive (12V positive) and black is GND (ground). Usually, the starter is connected to GND is the screws to the chassis. The chassis is always GND. NEVER connect red and black wires together, or mix them up! Although there is only 12V in the system, the amperage in these batteries is serious! Huge sparks if shorted and the battery goes dead.
Basic wiring, is 12V from battery via ignition key to starter solenoid. That way, the solenoid get’s 12V when the ignition key is turned to Start. It already has GND because it’s screwed to the chassis.
If you have zero knowledge about electrical wiring on an engine, then you could start by watching some videos about small engine wiring on YouTube. I suggest Donyboy73, THEMOWERMEDIC1 and Steve’s SmallEngineSaloon channels. Don, Jeremy and Steve are great guys and have a nice way of teaching.